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Negretti and Zambra were amongst the world's greatest instrument makers. Established in 1850 and based in London, they made innovative barometers for Charles Darwin's voyages on the Beagle, particularly designed to withstand the concussion of a ships heavy guns. In 1915 they developed a hand held weather forecaster made of ivorine which required a minimum of information to be input and yet proved to be more than 90% accurate over a twelve hour period. The forecaster quickly became popular with soldiers, explorers and everyone engaged in outdoor activities.
Click Photo for Zambretti Forecaster
Recently the algorithm used for the Zambretti hand held device was written into a computer program and you can now try it out for yourself. Just click on the picture above and enter the information. You will need to know the barometric pressure in your area and the pressure trend, (steady, rising or falling), together with the wind direction and the month of the year; thats all! The forecast is most accurate when made at 0900 hours. See how you get on.
NEWS! If you would like to buy a modern version of the pocket forecaster to take with you on your outdoor activities then click on the photo above to go to the Ebay website. The forecaster costs £7.99 plus £2.00 postage.